1. Field of Invention
Vertical upstanding lamps, such as the one shown in FIG. 1, have become very popular in recent years. In spite of such popularity these lamps present a fire hazard when in presence of flammable objects. The reasons for this high fire risk are the following:
First, the temperature of the lamp, usually a 300 to 600 watt quartz lamp, is very high;
and second, the center of gravity of these modern lamp designs is very high which makes the lamp very unstable and prone to falling.
The combination of high temperatures plus poor stability increases the probability that the light bulb may come into contact with a flammable surface, such as carpet, which in turn can ignite a fire.
While, in this patent application a safety mechanism as applied to a vertically standing quartz lamp as the preferred embodiment of the invention is described, the safety mechanism is also applicable to any type of lamp which poses a fire hazard when it falls.
2. Description of Prior Art
The idea of interrupting the electrical current to a device has been successfully applied to other hazardous conditions, which arise from the operation of electric devices. In U.S. Pat. No. 5,576,683, Rose describes a Thermostat with thermal insulator for protection against overheating in which the electrical current is cut after a threshold temperature has been reached. In U.S. Pat. No. 4,973,936, Dimpault and Darcy describe a thermal switch for short circuit protection of batteries, which cuts the battery current in the event of a short circuit.
In general, the concept of a circuit breaker which interrupts the electrical current when a hazardous situation arises (machine is blocked, the current is excessive, the temperature is above a threshold) has been used in the referred patents and in other inventions. This idea is also of common use in the protection of electrical installations in houses and other buildings.
In the case of vertically standing lamps, the protection against the fire hazard in case of a fall has not been addressed using the general idea of interrupting the electric current to remove the source of heat. In order to increase the safety of vertically standing lamps such as the one shown in FIG. 1, these lamps come assembled with a protective grid on the light bulb as shown in FIG. 2. This grid can be made either of plastic, metal or other material. The purpose of the grid is to prevent the light bulb from coming directly into contact with the flammable materials in case of a fall. The grid effectively reduces the fire hazard by isolating the source of heat from the flammable materials rather than eliminating the source of heat. Because the grid only isolates the source of heat rather than eliminating it, there is still a certain degree of risk since the grid becomes hot and may ignite a highly flammable material such as paper. There have been many incidents in which a lamp, such as the one described in this application, has caused a fire when it fell on top of a flammable surface.